Class Font

The Font class represents fonts, which are used to render text in a visible way. A font provides the information needed to map sequences of characters to sequences of glyphs and to render sequences of glyphs on Graphics and Component objects.

Characters and Glyphs

A character is a symbol that represents an item such as a letter, a digit, or punctuation in an abstract way. For example, 'g', LATIN SMALL LETTER G, is a character.

A glyph is a shape used to render a character or a sequence of characters. In simple writing systems, such as Latin, typically one glyph represents one character. In general, however, characters and glyphs do not have one-to-one correspondence. For example, the character 'á' LATIN SMALL LETTER A WITH ACUTE, can be represented by two glyphs: one for 'a' and one for '´'. On the other hand, the two-character string "fi" can be represented by a single glyph, an "fi" ligature. In complex writing systems, such as Arabic or the South and South-East Asian writing systems, the relationship between characters and glyphs can be more complicated and involve context-dependent selection of glyphs as well as glyph reordering. A font encapsulates the collection of glyphs needed to render a selected set of characters as well as the tables needed to map sequences of characters to corresponding sequences of glyphs.

Physical and Logical Fonts

The Java Platform distinguishes between two kinds of fonts: physical fonts and logical fonts.

Physical fonts are the actual font libraries containing glyph data and tables to map from character sequences to glyph sequences, using a font technology such as TrueType or PostScript Type 1. All implementations of the Java Platform must support TrueType fonts; support for other font technologies is implementation dependent. Physical fonts may use names such as Helvetica, Palatino, HonMincho, or any number of other font names. Typically, each physical font supports only a limited set of writing systems, for example, only Latin characters or only Japanese and Basic Latin. The set of available physical fonts varies between configurations. Applications that require specific fonts can bundle them and instantiate them using the createFont method.

Logical fonts are the five font families defined by the Java platform which must be supported by any Java runtime environment: Serif, SansSerif, Monospaced, Dialog, and DialogInput. These logical fonts are not actual font libraries. Instead, the logical font names are mapped to physical fonts by the Java runtime environment. The mapping is implementation and usually locale dependent, so the look and the metrics provided by them vary. Typically, each logical font name maps to several physical fonts in order to cover a large range of characters.

Peered AWT components, such as Label and TextField, can only use logical fonts.

For a discussion of the relative advantages and disadvantages of using physical or logical fonts, see the Internationalization FAQ document.

Font Faces and Names

A Font can have many faces, such as heavy, medium, oblique, gothic and regular. All of these faces have similar typographic design.

There are three different names that you can get from a Font object. The logical font name is simply the name that was used to construct the font. The font face name, or just font name for short, is the name of a particular font face, like Helvetica Bold. The family name is the name of the font family that determines the typographic design across several faces, like Helvetica.

The Font class represents an instance of a font face from a collection of font faces that are present in the system resources of the host system. As examples, Arial Bold and Courier Bold Italic are font faces. There can be several Font objects associated with a font face, each differing in size, style, transform and font features.

The getAllFonts method of the GraphicsEnvironment class returns an array of all font faces available in the system. These font faces are returned as Font objects with a size of 1, identity transform and default font features. These base fonts can then be used to derive new Font objects with varying sizes, styles, transforms and font features via the deriveFont methods in this class.

Font and TextAttribute

Font supports most TextAttributes. This makes some operations, such as rendering underlined text, convenient since it is not necessary to explicitly construct a TextLayout object. Attributes can be set on a Font by constructing or deriving it using a Map of TextAttribute values.

The values of some TextAttributes are not serializable, and therefore attempting to serialize an instance of Font that has such values will not serialize them. This means a Font deserialized from such a stream will not compare equal to the original Font that contained the non-serializable attributes. This should very rarely pose a problem since these attributes are typically used only in special circumstances and are unlikely to be serialized.

FOREGROUND and BACKGROUND use Paint values. The subclass Color is serializable, while GradientPaint and TexturePaint are not.

CHAR_REPLACEMENT uses GraphicAttribute values. The subclasses ShapeGraphicAttribute and ImageGraphicAttribute are not serializable.

INPUT_METHOD_HIGHLIGHT uses InputMethodHighlight values, which are not serializable. See InputMethodHighlight.

Clients who create custom subclasses of Paint and GraphicAttribute can make them serializable and avoid this problem. Clients who use input method highlights can convert these to the platform-specific attributes for that highlight on the current platform and set them on the Font as a workaround.

Several attributes will cause additional rendering overhead and potentially invoke layout. If a Font has such attributes, the hasLayoutAttributes() method will return true.

Note: Font rotations can cause text baselines to be rotated. In order to account for this (rare) possibility, font APIs are specified to return metrics and take parameters 'in baseline-relative coordinates'. This maps the 'x' coordinate to the advance along the baseline, (positive x is forward along the baseline), and the 'y' coordinate to a distance along the perpendicular to the baseline at 'x' (positive y is 90 degrees clockwise from the baseline vector). APIs for which this is especially important are called out as having 'baseline-relative coordinates.'

Fields

DIALOG

public static final String DIALOG

A String constant for the canonical family name of the logical font "Dialog". It is useful in Font construction to provide compile-time verification of the name.

Since:

1.6

DIALOG_INPUT

public static final String DIALOG_INPUT

A String constant for the canonical family name of the logical font "DialogInput". It is useful in Font construction to provide compile-time verification of the name.

Since:

1.6

SANS_SERIF

public static final String SANS_SERIF

A String constant for the canonical family name of the logical font "SansSerif". It is useful in Font construction to provide compile-time verification of the name.

Since:

1.6

SERIF

public static final String SERIF

A String constant for the canonical family name of the logical font "Serif". It is useful in Font construction to provide compile-time verification of the name.

Since:

1.6

MONOSPACED

public static final String MONOSPACED

A String constant for the canonical family name of the logical font "Monospaced". It is useful in Font construction to provide compile-time verification of the name.

Since:

1.6

PLAIN

public static final int PLAIN

The plain style constant.

BOLD

public static final int BOLD

The bold style constant. This can be combined with the other style constants (except PLAIN) for mixed styles.

ITALIC

public static final int ITALIC

The italicized style constant. This can be combined with the other style constants (except PLAIN) for mixed styles.

ROMAN_BASELINE

public static final int ROMAN_BASELINE

The baseline used in most Roman scripts when laying out text.

CENTER_BASELINE

public static final int CENTER_BASELINE

The baseline used in ideographic scripts like Chinese, Japanese, and Korean when laying out text.

HANGING_BASELINE

public static final int HANGING_BASELINE

The baseline used in Devanigiri and similar scripts when laying out text.

TRUETYPE_FONT

public static final int TRUETYPE_FONT

Identify a font resource of type TRUETYPE. Used to specify a TrueType font resource to the createFont(int, java.io.InputStream) method. The TrueType format was extended to become the OpenType format, which adds support for fonts with Postscript outlines, this tag therefore references these fonts, as well as those with TrueType outlines.

pointSize

LAYOUT_LEFT_TO_RIGHT

A flag to layoutGlyphVector indicating that text is left-to-right as determined by Bidi analysis.

LAYOUT_RIGHT_TO_LEFT

public static final int LAYOUT_RIGHT_TO_LEFT

A flag to layoutGlyphVector indicating that text is right-to-left as determined by Bidi analysis.

LAYOUT_NO_START_CONTEXT

public static final int LAYOUT_NO_START_CONTEXT

A flag to layoutGlyphVector indicating that text in the char array before the indicated start should not be examined.

LAYOUT_NO_LIMIT_CONTEXT

public static final int LAYOUT_NO_LIMIT_CONTEXT

A flag to layoutGlyphVector indicating that text in the char array after the indicated limit should not be examined.

Constructors

Font

public Font(String name,
int style,
int size)

Creates a new Font from the specified name, style and point size.

The font name can be a font face name or a font family name. It is used together with the style to find an appropriate font face. When a font family name is specified, the style argument is used to select the most appropriate face from the family. When a font face name is specified, the face's style and the style argument are merged to locate the best matching font from the same family. For example if face name "Arial Bold" is specified with style Font.ITALIC, the font system looks for a face in the "Arial" family that is bold and italic, and may associate the font instance with the physical font face "Arial Bold Italic". The style argument is merged with the specified face's style, not added or subtracted. This means, specifying a bold face and a bold style does not double-embolden the font, and specifying a bold face and a plain style does not lighten the font.

If no face for the requested style can be found, the font system may apply algorithmic styling to achieve the desired style. For example, if ITALIC is requested, but no italic face is available, glyphs from the plain face may be algorithmically obliqued (slanted).

Font name lookup is case insensitive, using the case folding rules of the US locale.

If the name parameter represents something other than a logical font, i.e. is interpreted as a physical font face or family, and this cannot be mapped by the implementation to a physical font or a compatible alternative, then the font system will map the Font instance to "Dialog", such that for example, the family as reported by getFamily will be "Dialog".

Parameters:

name - the font name. This can be a font face name or a font family name, and may represent either a logical font or a physical font found in this GraphicsEnvironment. The family names for logical fonts are: Dialog, DialogInput, Monospaced, Serif, or SansSerif. Pre-defined String constants exist for all of these names, for example, DIALOG. If name is null, the logical font name of the new Font as returned by getName() is set to the name "Default".

style - the style constant for the Font The style argument is an integer bitmask that may be PLAIN, or a bitwise union of BOLD and/or ITALIC (for example, ITALIC or BOLD|ITALIC). If the style argument does not conform to one of the expected integer bitmasks then the style is set to PLAIN.

Font

Creates a new Font with the specified attributes. Only keys defined in TextAttribute are recognized. In addition the FONT attribute is not recognized by this constructor (see getAvailableAttributes()). Only attributes that have values of valid types will affect the new Font.

getFont

Returns a Font appropriate to the attributes. If attributescontains a FONT attribute with a valid Font as its value, it will be merged with any remaining attributes. See TextAttribute.FONT for more information.

createFont

Returns a new Font using the specified font type and input data. The new Font is created with a point size of 1 and style PLAIN. This base font can then be used with the deriveFont methods in this class to derive new Font objects with varying sizes, styles, transforms and font features. This method does not close the InputStream.

To make the Font available to Font constructors the returned Font must be registered in the GraphicsEnviroment by calling registerFont(Font).

Parameters:

fontFormat - the type of the Font, which is TRUETYPE_FONT if a TrueType resource is specified. or TYPE1_FONT if a Type 1 resource is specified.

fontStream - an InputStream object representing the input data for the font.

createFont

Returns a new Font using the specified font type and the specified font file. The new Font is created with a point size of 1 and style PLAIN. This base font can then be used with the deriveFont methods in this class to derive new Font objects with varying sizes, styles, transforms and font features.

Parameters:

fontFormat - the type of the Font, which is TRUETYPE_FONT if a TrueType resource is specified or TYPE1_FONT if a Type 1 resource is specified. So long as the returned font, or its derived fonts are referenced the implementation may continue to access fontFile to retrieve font data. Thus the results are undefined if the file is changed, or becomes inaccessible.

To make the Font available to Font constructors the returned Font must be registered in the GraphicsEnviroment by calling registerFont(Font).

getTransform

public AffineTransform getTransform()

Returns a copy of the transform associated with this Font. This transform is not necessarily the one used to construct the font. If the font has algorithmic superscripting or width adjustment, this will be incorporated into the returned AffineTransform.

Typically, fonts will not be transformed. Clients generally should call isTransformed() first, and only call this method if isTransformed returns true.

Returns:

an AffineTransform object representing the transform attribute of this Font object.

getFamily

public String getFamily()

Returns the family name of this Font.

The family name of a font is font specific. Two fonts such as Helvetica Italic and Helvetica Bold have the same family name, Helvetica, whereas their font face names are Helvetica Bold and Helvetica Italic. The list of available family names may be obtained by using the GraphicsEnvironment.getAvailableFontFamilyNames() method.

Use getName to get the logical name of the font. Use getFontName to get the font face name of the font.

getFamily

public String getFamily(Locale l)

Returns the family name of this Font, localized for the specified locale.

The family name of a font is font specific. Two fonts such as Helvetica Italic and Helvetica Bold have the same family name, Helvetica, whereas their font face names are Helvetica Bold and Helvetica Italic. The list of available family names may be obtained by using the GraphicsEnvironment.getAvailableFontFamilyNames() method.

Use getFontName to get the font face name of the font.

Parameters:

l - locale for which to get the family name

Returns:

a String representing the family name of the font, localized for the specified locale.

getFontName

public String getFontName()

Returns the font face name of this Font. For example, Helvetica Bold could be returned as a font face name. Use getFamily to get the family name of the font. Use getName to get the logical name of the font.

getStyle

getSize

public int getSize()

Returns the point size of this Font, rounded to an integer. Most users are familiar with the idea of using point size to specify the size of glyphs in a font. This point size defines a measurement between the baseline of one line to the baseline of the following line in a single spaced text document. The point size is based on typographic points, approximately 1/72 of an inch.

The Java(tm)2D API adopts the convention that one point is equivalent to one unit in user coordinates. When using a normalized transform for converting user space coordinates to device space coordinates 72 user space units equal 1 inch in device space. In this case one point is 1/72 of an inch.

hasLayoutAttributes

getFont

public static Font getFont(String nm)

Returns a Font object from the system properties list. nm is treated as the name of a system property to be obtained. The String value of this property is then interpreted as a Font object according to the specification of Font.decode(String) If the specified property is not found, or the executing code does not have permission to read the property, null is returned instead.

Parameters:

nm - the property name

Returns:

a Font object that the property name describes, or null if no such property exists.

decode

Returns the Font that the str argument describes. To ensure that this method returns the desired Font, format the str parameter in one of these ways

fontname-style-pointsize

fontname-pointsize

fontname-style

fontname

fontname style pointsize

fontname pointsize

fontname style

fontname

in which style is one of the four case-insensitive strings: "PLAIN", "BOLD", "BOLDITALIC", or "ITALIC", and pointsize is a positive decimal integer representation of the point size. For example, if you want a font that is Arial, bold, with a point size of 18, you would call this method with: "Arial-BOLD-18". This is equivalent to calling the Font constructor : new Font("Arial", Font.BOLD, 18); and the values are interpreted as specified by that constructor.

A valid trailing decimal field is always interpreted as the pointsize. Therefore a fontname containing a trailing decimal value should not be used in the fontname only form.

If a style name field is not one of the valid style strings, it is interpreted as part of the font name, and the default style is used.

Only one of ' ' or '-' may be used to separate fields in the input. The identified separator is the one closest to the end of the string which separates a valid pointsize, or a valid style name from the rest of the string. Null (empty) pointsize and style fields are treated as valid fields with the default value for that field.

Some font names may include the separator characters ' ' or '-'. If str is not formed with 3 components, e.g. such that style or pointsize fields are not present in str, and fontname also contains a character determined to be the separator character then these characters where they appear as intended to be part of fontname may instead be interpreted as separators so the font name may not be properly recognised.

The default size is 12 and the default style is PLAIN. If str does not specify a valid size, the returned Font has a size of 12. If str does not specify a valid style, the returned Font has a style of PLAIN. If you do not specify a valid font name in the str argument, this method will return a font with the family name "Dialog". To determine what font family names are available on your system, use the GraphicsEnvironment.getAvailableFontFamilyNames() method. If str is null, a new Font is returned with the family name "Dialog", a size of 12 and a PLAIN style.

Parameters:

str - the name of the font, or null

Returns:

the Font object that str describes, or a new default Font if str is null.

getFont

public static Font getFont(String nm,
Font font)

Gets the specified Font from the system properties list. As in the getProperty method of System, the first argument is treated as the name of a system property to be obtained. The String value of this property is then interpreted as a Font object.

The property value should be one of the forms accepted by Font.decode(String) If the specified property is not found, or the executing code does not have permission to read the property, the font argument is returned instead.

getNumGlyphs

Returns the number of glyphs in this Font. Glyph codes for this Font range from 0 to getNumGlyphs() - 1.

Returns:

the number of glyphs in this Font.

Since:

1.2

getMissingGlyphCode

public int getMissingGlyphCode()

Returns the glyphCode which is used when this Font does not have a glyph for a specified unicode code point.

Returns:

the glyphCode of this Font.

Since:

1.2

getBaselineFor

public byte getBaselineFor(char c)

Returns the baseline appropriate for displaying this character.

Large fonts can support different writing systems, and each system can use a different baseline. The character argument determines the writing system to use. Clients should not assume all characters use the same baseline.

canDisplayUpTo

public int canDisplayUpTo(String str)

Indicates whether or not this Font can display a specified String. For strings with Unicode encoding, it is important to know if a particular font can display the string. This method returns an offset into the Stringstr which is the first character this Font cannot display without using the missing glyph code. If the Font can display all characters, -1 is returned.

Parameters:

str - a String object

Returns:

an offset into str that points to the first character in str that this Font cannot display; or -1 if this Font can display all characters in str.

Since:

1.2

canDisplayUpTo

public int canDisplayUpTo(char[] text,
int start,
int limit)

Indicates whether or not this Font can display the characters in the specified text starting at start and ending at limit. This method is a convenience overload.

hasUniformLineMetrics

public boolean hasUniformLineMetrics()

Checks whether or not this Font has uniform line metrics. A logical Font might be a composite font, which means that it is composed of different physical fonts to cover different code ranges. Each of these fonts might have different LineMetrics. If the logical Font is a single font then the metrics would be uniform.

getStringBounds

public Rectangle2D getStringBounds(String str,
FontRenderContext frc)

Returns the logical bounds of the specified String in the specified FontRenderContext. The logical bounds contains the origin, ascent, advance, and height, which includes the leading. The logical bounds does not always enclose all the text. For example, in some languages and in some fonts, accent marks can be positioned above the ascent or below the descent. To obtain a visual bounding box, which encloses all the text, use the getBounds method of TextLayout.

Note: The returned bounds is in baseline-relative coordinates (see class notes).

Parameters:

str - the specified String

frc - the specified FontRenderContext

Returns:

a Rectangle2D that is the bounding box of the specified String in the specified FontRenderContext.

getStringBounds

Returns the logical bounds of the specified String in the specified FontRenderContext. The logical bounds contains the origin, ascent, advance, and height, which includes the leading. The logical bounds does not always enclose all the text. For example, in some languages and in some fonts, accent marks can be positioned above the ascent or below the descent. To obtain a visual bounding box, which encloses all the text, use the getBounds method of TextLayout.

Note: The returned bounds is in baseline-relative coordinates (see class notes).

Parameters:

str - the specified String

beginIndex - the initial offset of str

limit - the end offset of str

frc - the specified FontRenderContext

Returns:

a Rectangle2D that is the bounding box of the specified String in the specified FontRenderContext.

Throws:

IndexOutOfBoundsException - if beginIndex is less than zero, or limit is greater than the length of str, or beginIndex is greater than limit.

getStringBounds

Returns the logical bounds of the specified array of characters in the specified FontRenderContext. The logical bounds contains the origin, ascent, advance, and height, which includes the leading. The logical bounds does not always enclose all the text. For example, in some languages and in some fonts, accent marks can be positioned above the ascent or below the descent. To obtain a visual bounding box, which encloses all the text, use the getBounds method of TextLayout.

Note: The returned bounds is in baseline-relative coordinates (see class notes).

Parameters:

chars - an array of characters

beginIndex - the initial offset in the array of characters

limit - the end offset in the array of characters

frc - the specified FontRenderContext

Returns:

a Rectangle2D that is the bounding box of the specified array of characters in the specified FontRenderContext.

Throws:

IndexOutOfBoundsException - if beginIndex is less than zero, or limit is greater than the length of chars, or beginIndex is greater than limit.

getStringBounds

Returns the logical bounds of the characters indexed in the specified CharacterIterator in the specified FontRenderContext. The logical bounds contains the origin, ascent, advance, and height, which includes the leading. The logical bounds does not always enclose all the text. For example, in some languages and in some fonts, accent marks can be positioned above the ascent or below the descent. To obtain a visual bounding box, which encloses all the text, use the getBounds method of TextLayout.

Note: The returned bounds is in baseline-relative coordinates (see class notes).

Parameters:

ci - the specified CharacterIterator

beginIndex - the initial offset in ci

limit - the end offset in ci

frc - the specified FontRenderContext

Returns:

a Rectangle2D that is the bounding box of the characters indexed in the specified CharacterIterator in the specified FontRenderContext.

Throws:

IndexOutOfBoundsException - if beginIndex is less than the start index of ci, or limit is greater than the end index of ci, or beginIndex is greater than limit

createGlyphVector

Creates a GlyphVector by mapping characters to glyphs one-to-one based on the Unicode cmap in this Font. This method does no other processing besides the mapping of glyphs to characters. This means that this method is not useful for some scripts, such as Arabic, Hebrew, Thai, and Indic, that require reordering, shaping, or ligature substitution.

Parameters:

frc - the specified FontRenderContext

str - the specified String

Returns:

a new GlyphVector created with the specified String and the specified FontRenderContext.

createGlyphVector

Creates a GlyphVector by mapping characters to glyphs one-to-one based on the Unicode cmap in this Font. This method does no other processing besides the mapping of glyphs to characters. This means that this method is not useful for some scripts, such as Arabic, Hebrew, Thai, and Indic, that require reordering, shaping, or ligature substitution.

Parameters:

frc - the specified FontRenderContext

chars - the specified array of characters

Returns:

a new GlyphVector created with the specified array of characters and the specified FontRenderContext.

createGlyphVector

Creates a GlyphVector by mapping the specified characters to glyphs one-to-one based on the Unicode cmap in this Font. This method does no other processing besides the mapping of glyphs to characters. This means that this method is not useful for some scripts, such as Arabic, Hebrew, Thai, and Indic, that require reordering, shaping, or ligature substitution.

Parameters:

frc - the specified FontRenderContext

ci - the specified CharacterIterator

Returns:

a new GlyphVector created with the specified CharacterIterator and the specified FontRenderContext.

createGlyphVector

Creates a GlyphVector by mapping characters to glyphs one-to-one based on the Unicode cmap in this Font. This method does no other processing besides the mapping of glyphs to characters. This means that this method is not useful for some scripts, such as Arabic, Hebrew, Thai, and Indic, that require reordering, shaping, or ligature substitution.

Parameters:

frc - the specified FontRenderContext

glyphCodes - the specified integer array

Returns:

a new GlyphVector created with the specified integer array and the specified FontRenderContext.

layoutGlyphVector

Returns a new GlyphVector object, performing full layout of the text if possible. Full layout is required for complex text, such as Arabic or Hindi. Support for different scripts depends on the font and implementation.

Layout requires bidi analysis, as performed by Bidi, and should only be performed on text that has a uniform direction. The direction is indicated in the flags parameter,by using LAYOUT_RIGHT_TO_LEFT to indicate a right-to-left (Arabic and Hebrew) run direction, or LAYOUT_LEFT_TO_RIGHT to indicate a left-to-right (English) run direction.

In addition, some operations, such as Arabic shaping, require context, so that the characters at the start and limit can have the proper shapes. Sometimes the data in the buffer outside the provided range does not have valid data. The values LAYOUT_NO_START_CONTEXT and LAYOUT_NO_LIMIT_CONTEXT can be added to the flags parameter to indicate that the text before start, or after limit, respectively, should not be examined for context.

All other values for the flags parameter are reserved.

Parameters:

frc - the specified FontRenderContext

text - the text to layout

start - the start of the text to use for the GlyphVector

limit - the limit of the text to use for the GlyphVector

flags - control flags as described above

Returns:

a new GlyphVector representing the text between start and limit, with glyphs chosen and positioned so as to best represent the text